Aimophila ruficeps
rufous-crowned sparrow

Rufous-crowned sparrows are found from mid to southern California through northern Baja California in the coastal areas to southern Mexico, as well as many other parts of the American Southwest, excluding northeastern Arizona and northwestern New Mexico. These birds range as far east as mid-eastern Texas and as far north as southern Utah and Colorado. (Collins, 1999; Peterson and Peterson, 1990; Robbins, et al., 1983)

This species inhabits arid, rocky, open areas with varying elevation and heterogeneous vegetation, including low grasses and shrubbery. They are also found in open pine and oak forests. If a winter is particularly cold, these birds may move south or lower in elevation, but they do not move far from their breeding grounds. (Collins, 1999; Peterson and Peterson, 1990; Robbins, et al., 1983; Collins, 1999; Peterson and Peterson, 1990; Robbins, et al., 1983)

Rufous-crowned sparrows are medium-sized birds with red-capped heads and beige-gray breasts. They have black stripes on either side of their solid, gray-white throat. Males tend to have slightly larger wingspans and tail length than females. (Collins, 1999; Peterson and Peterson, 1990; Robbins, et al., 1983; Sibley, 2001; Sibley, 2003)

Similiar species include Aimophila rufescens, Aimophila notosticta, Spizella passerina, and Zonotrichia leucophrys. Rufous-crowned sparrows differ from these species in their red-brown cap and solid-colored breast. American tree sparrows (Spizella arborea) also have the red cap, but do not have a rounded tail. Sparrows in the genus Aimophila can also be distinguished from other sparrows in the range of rufous-crowned sparrows by their beaks and tails, which are longer in proportion to their body size than in other sparrows. Males and females ares similar in color, but males tend to be larger than females. (Collins, 1999; Peterson and Peterson, 1990; Robbins, et al., 1983; Sibley, 2001; Sibley, 2003)

These birds find a mate in the spring and stay with the same mate through the winter and often through following mating seasons. Males attract a mate by singing from a visible perch or while flying. The mates sing duets together and to each other when they reunite in their territory. These songs are used for recognition and to strengthen the bond between them. Males are territorial during mating season, are not exceptionally aggressive in protecting their territory. (Collins, 1999; Ehrlich, et al., 1988; Morrison, et al., 2004)

Reproduction varies by region and year-to-year with weather changes. For example, rainy weather seems to act as a cue for nesting, so nesting begins in early summer in Mexico, but much earlier in California, where rains begin earlier. The dates when eggs are laid also vary by region. Birds in California lay eggs earlier (Mar 11- Jul 10) than those in Texas (Apr 4- Sept 26). In some parts of their range, rufous-crowned sparrows nest twice per year based on rain patterns. It seems that these sparrows breed only when food is available (dependent on rainfall), which could result in increased survivorship of young.

Only female sparrows build nests. Nests are constructed of grass, bark, twigs, and hair, and are usually built in a shallow concavity in the ground. Once the eggs are laid, the female incubates until hatching. The young are altricial when hatched, and both parents help to find food and feed the hatchlings.

When the young birds leave the nest, they are as yet unable to fly and they continue to depend on their parents for food. The amount of time the fledglings are dependent on their parents is unknown, but they may not become independent until winter. The age of sexual reproductive maturity is also unknown, but it is assumed that the birds are over one year old before they reproduce.

Rufous-crowned sparrows tend to return to the same breeding ground year after year once a territory is chosen as an adult. (Collins, 1999; Ehrlich, et al., 1988; Morrison, et al., 2004)

Females incubate eggs for 11 to 13 days. They stay with the eggs except when foraging, at which time the male sparrow sometimes joins her. Females will abandon the nest easily if it is disturbed, and will not attack intruders. However, females do attempt to ward off those who come too close to the nest by flapping her wings and making loud noises.

Once the eggs hatch, the female is the exclusive brooder. Both male and female sparrows find food for the young. They will feed the offspring for an unknown period of time, even after the young leave the nest. (Collins, 1999; Ehrlich, et al., 1988)

The longest recorded lifespan for a rufous-crowned sparrow is 3 years and 2 months. (Collins, 1999)

Rufous-crowned sparrows tend to use hopping and running as their primary mode of locomotion. Flight is rarely used; the sparrows are clumsy in their flight and generally don't fly long distances. These birds use their beaks to brush down their feathers, and will bathe when shallow water is present. They forage by pecking at the ground. Family units form for some time after breeding. These groups range in size from 4 to 6 individuals. During the breeding season, birds are observed in pairs within their territories. Otherwise, these sparrows are usually nonsocial, and do not form flocks. They are territorial during mating season, but not aggressive. (Collins, 1999)

The size of a rufous-crowned sparrow territory can range from 0.77 ha to 0.89 ha. The home range in this species includes the area protected as territory. These areas include the nest and surrounding area, the area where foraging occurs, and the area occupied by dependent fledglings. (Collins, 1999)

Rufous-crowned sparrows have voices that have been described as "hoarse" and their call is a descending succession of staccato notes. This call, described by Collins (1999) as the Primary Song, is probably used by males to announce their territory and to attract a female mate. Rufous-crowned sparrows sing at a lower pitch during the nonbreeding season. Visual signs such as posture and vocal calls are used by the birds at specified times for several purposes. For example, males use a certain call when chasing intruders from their territory. Both males and females use vocal calls to give predator warnings. Warning calls are often nasal noises described as sounding like "dear." Aggressive sounds and postures are used during competition over territory between two males. Mates also sing songs to one another in order to recognize each other or to strengthen the pair's relationship. (Collins, 1999; Sibley, 2001; Sibley, 2003)

Food habits depend on region and time of year. Grass, seeds and insects are primary foods. Rufous-crowned sparrows eat more plants such as knotweed (Polyugonum), chickweed (Stellaria media), filaree (Erodium), dock (Rumex), and wild oats (Avena) during the summer and spring. Grasshoppers (Acrididae), ground beetles (Carabidae), and ants (Formicidae) become a larger percentage of their diet during other parts of the year. (Collins, 1999)

Domestic cats (Felis silvestris) prey on rufous-crowned sparrows. Behaviors towards Mexican jays (Aphelocoma ultramarina) suggest a possible predator/prey relationship. Other possible predators include American kestrels (Falco sparverius), white-tailed kites (Elanus leucurus), sharp-shinned hawks (Accipiter striatus), and Cooper's hawks (Accipiter cooperii). Snakes are probably important predators of eggs and nestlings, as they are in other Aimophila species. (Collins, 1999; Morrison, et al., 2004)

Rufous-crowned sparrows are primary consumers, as they eat vegetation. They are also secondary consumers, as they eat insects as well. These sparrows are preyed on by domestic cats (Felis silvestris) and probably predatory birds and snakes. Rufous-crowned sparrows can be hosts for the nest parasite, brown-headed cowbirds (Molothrus ater), though this is uncommon. They are also parasitized by two species of ticks (Amblyomma americanum and Ixodes pacificus). (Collins, 1999)

These birds help to control insect populations through their feeding habits. (Collins, 1999)

There are no known adverse effects of Aimophila ruficeps on humans.

Although rufous-crowned sparrows are not considered endangered or threatened, loss of habitat through human expansion has limited their range and may affect populations. (Collins, 1999)